Apparatus for the concentration and/or sizing of mineral particles



F. J. TROMP APPARATUS FOR THE CONCENTRATION AND/OR SIZING OF MINERAL PARTICLES April 23, 1935.

Filed Oct. 11, 1933 2 Sheets-Sheet l April 23, 1935. F, J, TRQMP 3,999,000

APPARATUS FOR THE CONCENTRATION AND/OR SIZING 0F MINERAL PARTICLES Filed Oct. 11 1935 2 Sheets-Sheet 2 Patented Apr. 23, 1935 UNITED STATES APPARATUS FOR THE CONCENTRATION AND/ OR SIZING F MINERAL PARTICLES Felix Johan Tromp, Pretoria, Union of South Africa Application October 11,

1933, Serial No. 693,189

In Union of South Africa October 15, 1932 11 Claims.

lowing types of particles are so capable of being concentrated from mixtures containing the same.

(A) Particles having an appreciably greater specific gravity may be separated from other particles of lesser specific gravity but of approximately the same or larger size, and of approximately the same shape, for example:-Cassiterite, galena, pyrite, cholcapyrite, zinc blende, magnetite, wolframite, gold and platinum from quartz, also diamonds from alluvial quartz and 1 pyrite from coal.

(B) Particles substantially flat compared with the particles from which they are to be concentrated may be separated from particles which are approximately equidimensional and approximately of the same orlarger size, and approximately of the same or smaller specific gravity, for

example substantially flat quartz from morev equidimensional quartz and also shale from coal.

(C) Small particles may be separated from larger particles of substantially the same shape and specific gravity, for example small quartz particles may be separated from large quartz particles.

The apparatus consists of a trough, or a series of troughs placed in succession, suitably mounted, for example on rollers or supported by springs, so that the requisite shaking motion may be imparted to the trough or troughs. The trough comprisesa bottom, a back and two endboards, with the front side left open. The bottom of the trough is set at an angle to the horizontal in such a manner that the front open side is at a higher level than the o-ppositeedge which is joined to the back. In addition both ends of the trough slope up from a more or less central area. 7

A feeding box is provided at one end of the trough, and at the other end, known as the concentrate end, a gate is provided for removing the concentrated mineral particles, the other min.- eral particles discharging over the front open side near the feeding box, known as the tailings end.

. Thedischarge is facilitated by means of a gap in the front side of the bottom at the tailings end or by having the dimensions of the trough larger end, takes place.

The whole trough is moved to and fro, the motion being substantially a simple harmonic mo' tion substantially in a horizontal plane. Y The whole trough is set at an angle to the motion as will be more clearly explained from the'draw mgs.

For continuous working on a large scale it is advantageous to have a series of troughs in succession arranged so that the tailings from a higher or adjacent trough discharge into the feeding box of the next succeeding trough. In this arrangement the concentrated particles may be tapped off from each trough independently.

To enable the invention to be more readily understood and carried into practice, reference will now be made to the accompanying drawings in which like reference numerals refer to lik parts throughout all views.

In the drawings:

Fig. 1 is a plan view of a simple apparatus embodying the invention.

Fig.2 is a side elevation on Fig. 1.

Fig. 3 is an end elevation on Fig. 2.

Fig. 4 is a sectional View taken on line AB in Fig. 1. I

Fig. 5 is'a View looking in the direction of arrow F in Fig. 1 showing the trough only.

Fig. 6 is a plan view of an alternative construction for the trough.

' Fig. 7 is aplanto an enlargedscale of the tailings discharge gap showing the method of adjustment.

Fig. 8 is a sectional elevation on line CD of Fig. '7.

A suitable method.for adjusting the gap .IT is by means of a series of insertable slats 22. The ends of the slats are tongued as at 24, and are arranged to be a sliding fit in the grooves 23 provided at eachend of the gap H. The slats 22 may be fixed in position by screws or other fastening means inserted through the bottom of the trough and engaging the tongued ends thereof.

Referring to the drawings reference I denotes a frame constructed from any suitable material, mounted horizontally on rollers 2 running on railsor the like 3 and adapted to be reciprocated by any known means such as cranks attached. to the connecting rods 4. The trough 5 is'mounted obliquely across the frame 1 and is provided with afeed box 6 at one end and a concentrate dis charge aperture or gate 1 at the opposite end.

The feeding box is arranged in such a way that forming a trough-shaped box having the front side open.

The bottom of the trough is divided into three distinct areas, which to facilitate description may be called, the stratification area, the separation area, and the concentration area. The stratification area H is that portion of the trough in .the vicinity of the feed box 6, the separation area is the centre portion I2 of the trough, while the concentration area is the portion 13 adjacent the concentrate discharge aperture or gate 1. The stratification area I I slopes downwards towards the centre of the trough at a small angle M- to the horizontal, which may be from 2 to 5 degrees, the separation area i2 is substantially level while the concentration area l3 preferably slopes downwards towards the centre of the trough at a small angle l5 to the horizontal which may vary from 30 minutes to 4 degrees depending upon the material worked upon and other factors to be hereinafter disclosed, Results may also be obtained even if this portion of the trough slopes up to 2 degrees in the opposite direction i. e. downwards from the centre portion. I have found 1 degree 30 minutes to be a good average angle when the angle 20 is 30 degrees. A larger angle may be used when the material is fine. By referringto Figs. 1 and 4 of the drawings the arrangement of the bottom of the trough will be made clear:-In some cases the separation area l2 may have the same slope as the concentration area !3.

' A further essential feature of the invention is the tilting of the trough bodily in a rearward direction as clearly illustrated in Figs. 2 and 4, by which the bottom It) makes an angle i6 of preferably from a degree to 80 degrees to the horizontal which angle depends on the amplitude and the rate of reciprocation of the trough. A satisfactory angle for general working is eight degrees.

Commencing at or near the bottom of the stratification area II is a gap l'l extending part way along the front edge of the separation area I2. This is the tailings discharge aperture through which the tailings are discharged either to waste, or, in the case of a multiple trough machine, into the feed box of the succeeding trough. In Fig. 6, is shown an alternative construction wherein the front free edges of the bottom slope inwards from each end to a common point l9 adjacent the bottom of the Stratification area I l. The tailings in this case then discharge over a portion of the edge l8. Such discharge will of course be greatest near the point l9 and will gradually and progressively decrease to zero as the distance from the concentrate end diminishes.

An additional feature of the invention lies in the matter of the oblique angle 20 (Fig. 1) which the trough as a whole makes with a line at right angles to the direction of motion. The magnitude of this angle depends upon the material dealt with, upon the amplitude and rate of reciprocation, and upon the angular settings of the bottom of the trough. In practice I have found that an angle of thirty degrees gives good general results with coarse material. Concentration may however be obtained with angles from five degrees to as much as eighty degrees. For fine material an angle of 45 degrees is suitable. If this angle is used, angle l 6 may be increased to say 10 degrees. Provision may be made in the construction of the machine whereby this angle may be varied within limits to suit different working conditions. Generally the greater the angle 20 is made, the greater becomes angle l5, and vice versa.

The bottom of the trough is preferably composed or lined with a material which has a relatively rough surface, when coarse material is treated. Thus wood or rubber may be used for this purpose, or iron if its surface is comparatively rough. When a mixture of coarse and fine material is to be concentrated, the bottom and/or the back may be made of wire mesh or like screening material, by which arrangement all the dust and fine particles will be removed and only the larger particles allowed to concentrate. For finely comminuted material a smooth metal surface may be employed. Generally, for coarse particles, a rough surface gives better results. To illustrate the working of the trough, I may give the following example of the concentration of cassiterite from a mixture or" cassiterite and quartz of a size between 'I and 4 mm. Use a trough of about 10 it. long with the narrowest width about 17 inches, with a stroke of 9 inches and 126 strokes per minute. The surface of the bottom of the trough may be lined with wood or rubber.

The trough is kept in motion and the m xture fed on to the trough by way of the feed box 6. As the material moves down the sloping stratification area l i it begins to separate out according to the differences in thespecific gravities of the particles. The heavier particles tend to con entrate towards the back 8 of the trough, while the lighter particles tend to be displaced towards the front edge thereof. In addition, the particles at theback of the trough move up towards the concentration end of the trough in spite of its angle E5 to the horizontal. As more of the heavy mineral moves into the concentration area the lighter particles return towards the separation area i2 and ultimately pass away through gap ii. The heavier mattergradually concentrates opposite the discharge aperture or gate "l through which it may be periodically or continuously allowed to flowinto a suitable receptacle.

On the other hand it has been found that if a mixture of particles of type B is fed into the trough, the flat particles will collect at the concentration end. Again if the particles forming the mixture are of type C the smaller particles will move towards the concentration end of the trough.

The amplitude of the to and fro motion or the length of the stroke together with the speed of reciprocation, will depend generally on the dimension of the narrowest portion of the bottom of the trough, that is, the distance from the edge of the gap I1 to the back board 8 and must not be so great as to practically empty that portion of the trough opposite the gap 17, or in the modified construction that portion opposite the point is, when fresh material is not added continuously. In a trough used for different types of material, it will be an advantage to provide means for adjusting within limits, the width of the narrowest portion of the bottom at the tailings discharge. Generally, for a given stroke an increase of speed gives a more rapid separation, but the im rovement continues only up to a certain point. To enable optimum conditions to be reached in a machine designed to be used for the separation of different classes of material, it will be desirable to provide means for adjusting both the stroke and the rate of reciprocation, as well as the narrowest width of the bottom of the trough opposite gap ll. For fine materials this width must be less than for coarse materials.

It is not advisable to use this machine for mixtures which are too line, for example material such as slimes.

The end boards are preferably placed in line with the direction of motion, particularly the end board near the tailings or feed end of the trough.

For fine materials the mixture is preferably dried by heating before treatment to drive off any moisture which might cause packing of the particles and consequent interference with the efficient working of the invention.

For purposes of this invention coarse materials are considered to be those in which the majority of the particles are above one millimeter in size.

I have found that separation and concentration is accelerated if a certain width of the bottom of the trough adjacent the back board is made comparatively smooth. In practice this may be accomplished by lining this width with sheet metal and leaving the remainder or front portion of the bottom comparatively rough or covering it with rubber or the like.

What I claim is:-

1. Apparatus for the concentration and-separation from a dry comminuted mixture of particles of the kinds hereinbefore described, comprising an opensided trough having a substantially vertical back and substantially vertical ends set parallel with the line of motion, each end of the bottom of the trough, referred toa longitudinal direction, sloping from a substantially center area, and in a transverse direction the whole bottom being inclined downwards from the front open side towards the back, thereby forming three distinct areas, namely a stratification area, a separation area, and a concen tration area, a feeding box at the stratification end, there being a concentrate discharge aperture at the concentration end, and a tailings discharge provided over the front elevated edge of a narrowed portion of the inclined bottom positioned within the center separation area, nearer the feed end than the discharge end; the whole trough being set obliquely to the direction of motion and having means for imparting to it a continuous reciprocatory motion of simple harmonic type.

2. Apparatus as claimedin claim 1, wherein the tailings discharge is provided by forming the inclined bottom of the trough of narrower width adjacent the meeting line of the separation area with the stratification area.

3. Apparatus as claimed in claim 1, wherein the front edge of the inclined bottom of the trough slopes inward from each end to a common point on the meeting line of the separation area with the stratification and wherein the V- shaped gap so formedv provides the tailings discharge.

4. Apparatus as claimed in claim 1, wherein a mixture feeding box is arranged adjacent the stratification end of the trough and directed so that thematerial is fed into the trough at a point near the junction between the bottom and the back thereof.

5. Apparatus as claimed in claim 1, wherein means are provided for adjusting the width of the narrowed portion of the bottom forming the tailings discharge.

6. Apparatus as claimed in claim 1, wherein the angle which the trough as a whole makes with a line at right angles to the direction of the line of reciprocatory motion varies from between five and eighty degrees.

7. Apparatus as claimed in claim 1, wherein the angle of slope of the concentration area to the horizontal, longitudinally of the trough, varies from minus two degrees to plus four degrees.

8. Apparatus as claimed in claim 1, wherein the separation area has the same slope as the concentration area referred to a longitudinal direction with respect to the trough 9. Apparatus as claimed in claim 1, wherein the angle which the inclined bottom of the trough makes with the horizontal varies between half a degree and thirty'degrees.

10. Apparatus as claimed in claim 1, wherein both the bottom and the substantially vertical back of the trough are constructed from screen- FELIX JOI-IAN TROMP. 

